Thanks RiverRose and Amanita, that is good info and something I kind of wanted to know.
And thanks LR, I like the clarification on a rule that can be hard to pin down. I do, by the way, think it helps if the member posting has been around for awhile and is known to not be a spammer. Not that the rule always applies, I'm just saying that when it's a new member posting a link (or some other thing that looks spammy), they're bound to be more suspect due to being a new member. Hope that makes sense ...
Re: the Slate interview ... worth mentioning perhaps is that the book "Sex at Dawn," like Perel, points out that humans are known (more than we tend to realize) to cheat even when they're totally happy with their marriages. Interesting concept that an affair symbolizes a point in life where one desires to change.